Novel top‐gate zinc oxide thin‐film transistors (ZnO TFTs) for AMLCDs

Abstract— High‐performance top‐gate thin‐film transistors (TFTs) with a transparent zinc oxide (ZnO) channel have been developed. ZnO thin films used as active channels were deposited by rf magnetron sputtering. The electrical properties and thermal stability of the ZnO films are controlled by the deposition conditions. A gate insulator made of silicon nitride (SiN_x) was deposited on the ZnO films by conventional P‐CVD. A novel ZnO‐TFT process based on photolithography is proposed for AMLCDs. AMLCDs having an aperture ratio and pixel density comparable to those of a‐Si:H TFT‐LCDs are driven by ZnO TFTs using the same driving scheme of conventional AMLCDs.     

Boojums Connecting Singular and Continuous Vortices in Two-Component Bose-Einstein Condensates

A boojum is a topological defect that can form only on the surface of an ordered medium such as superfluid ³He and liquid crystals. By analogy with superfluid ³He, we numerically create boojums between two phases with different vortex structures in two-component BECs where the intercomponent interaction is spatially dependent. The detailed structure of the boojums is revealed by investigating its density distribution, effective superflow vorticity and pseudospin texture.     

Tachyon Condensation and Brane Annihilation in Bose-Einstein Condensates: Spontaneous Symmetry Breaking in Restricted Lower-Dimensional Subspace

In brane cosmology, the Big Bang is hypothesized to occur by the annihilation of the brane–anti-brane pair in a collision, where the branes are three-dimensional objects in a higher-dimensional Universe. Spontaneous symmetry breaking accompanied by the formation of lower-dimensional topological defects, e.g. cosmic strings, is triggered by the so-called ‘tachyon condensation’, where the existence of tachyons is attributable to the instability of the brane–anti-brane system. Here, we discuss the closest analogue of the tachyon condensation in atomic Bose–Einstein condensates. We consider annihilation of domain walls, namely branes, in strongly segregated two-component condensates, where one component is sandwiched by two domains of the other component. In this system, the process of the brane annihilation can be projected effectively as ferromagnetic ordering dynamics onto a two-dimensional space. Based on this correspondence, three-dimensional formation of vortices from a domain-wall annihilation is considered to be a kink formation due to spontaneous symmetry breaking in the two-dimensional space. We also discuss a mechanism to create a ‘vorton’ when the sandwiched component has a vortex string bridged between the branes. We hope that this study motivates experimental researches to realize this exotic phenomenon of spontaneous symmetry breaking in superfluid systems.     

Bending strength of concrete-filled narrow-width steel box girder

A new type of partially concrete filled steel box girder is proposed. The distance between the two webs is narrower than that of a conventional steel box girder, and concrete is filled inside the box girder at the intermediate supports of the continuous girder. Static bending loading tests were conducted with these new type girders, showing that the ultimate bending strength of the concrete filled steel box girder model was 40% larger than that of the steel box girder model. The ductility also increased about 8 times. The tests with the half concrete filled steel box girder model showed that the ultimate bending strength was 25% larger than the steel box girder model and the ductility was about 6.5 times larger. The half concrete filled steel box girder model without vertical stiffeners had the same ultimate bending strength of that of the girder with vertical stiffeners but the ductility was about half. The simple calculation method was developed using fibre models. The calculated results agreed with the test results and the calculation method has been verified.     

Synthesis of europium-doped yttrium hydroxide and yttrium oxide nanosheets

A new approach has been developed for the preparation of Y(OH)₃:Eu and Y₂O₃:Eu nanosheets using the sol–gel method and hydrothermal reactions. XRD patterns showed that the product was purely hexagonal-phase Y(OH)₃. TEM images revealed that the nanosheets are square shaped (1 × 1 μm²) with a thickness of several tens of nanometers. In addition, it was found that cubic-phase Y₂O₃ nanosheets can be obtained by calcination of Y(OH)₃ at 900 °C for 1 h. More importantly, the thus-prepared Y(OH)₃:Eu and Y₂O₃:Eu nanosheet phosphors were found to exhibit a relatively high photoluminescence (PL) intensity.     

Effect of Ti substitution on electrochemical properties of ZrNi alloy electrode for use in nickel-metal hydride batteries

Crystal structure and electrochemical properties of the Zr_1?xTi_xNi (0.05 ≤ x ≤ 0.5) alloys were investigated. X-ray diffraction spectra showed that the primary phase of all Zr_1?xTi_xNi alloys had the B33-type orthorhombic crystal structure, which was characteristic of ZrNi, and the unit cell volume of the primary phase linearly decreased with an increase in the x value. In the charge–discharge tests with the Zr_1?xTi_xNi alloy negative electrodes, the initial discharge curves for the alloys with x ≥ 0.3 had two plateaus. Both plateau potentials negatively shifted with an increase in the x value. The initial discharge capacity for the Zr_0.6Ti_0.4Ni alloy negative electrode was 349 mAh g^?1 at 25 mA g^?1 and 333 K, which was the highest in this study. The high-rate dischargeability and cycle performance were also improved by the partial replacement of Zr by Ti.     

Adaptive control of Wiener-type nonlinear systems using neural networks

This paper proposes new adaptive control schemes with neural networks for Weiner-type nonlinear systems which have output nonlinearity. First, by adopting a robust adaptive control law and a functional link network (FLN), we present an adaptive linearizing scheme as a primary step for a model reference control scheme, where the FLN compensates the output nonlinearity. Second, we analyze the stability of the adaptive linearizing scheme by using a robust adaptive control technique, and demonstrate that all of the parameters are bounded and that the boundedness of all of the signals in the closed loop is guaranteed under some reasonable conditions. Third, based on the linearizing scheme, we present a new direct model reference adaptive control scheme by choosing the reference output appropriately. The stability of the system is guaranteed under several conditions in a similar manner. Finally, we illustrate the effectiveness of the proposed scheme through some numerical examples. © 1998 Scripta Technica. Electr Eng Jpn, 122(1): 37–48, 1998     

Design of a Full-Consensus Glutamate Decarboxylase and Its Application to GABA Biosynthesis

Glutamate decarboxylase (GAD) catalyses the decarboxylation of L-glutamate to gamma-aminobutyric acid (GABA). Improvement of the enzymatic properties of GAD is important for the low-cost synthesis of GABA. In this study, utilizing sequences of enzymes homologous with GAD from lactic acid bacteria, highly mutated GADs were designed using sequence-based protein design methods. Two mutated GADs, FcGAD and AncGAD, generated by full-consensus design and ancestral sequence reconstruction, had more desirable properties than native GADs. With respect to thermal stability, the half-life of the designed GADs was about 10 °C higher than that of native GAD. The productivity of FcGAD was considerably higher than those of known GADs; more than 250 mg/L of purified enzyme could be produced in the E. coli expression system. In a production test using 26.4 g of l -glutamate and 3.0 g of resting cells, 17.2 g of GABA could be prepared within one hour, without purification, in a one-pot synthesis.     

Definition of an Index Parameter To Screen Highly Functional Enzymes Derived from a Biochemical and Thermodynamic Analysis of Ancestral meso-Diaminopimelate Dehydrogenases

Sequence-based protein design approaches are being adopted to generate highly functional enzymes; however, screening the enzymes remains a time-consuming task. In this study, by analyzing the enzymatic properties of four ancestral meso-2,6-diaminopimelate dehydrogenases (AncDAPDHs), AncDAPDH-N1, -N2, -N3, and -N4, we attempted to define a new index parameter that is helpful for efficiently screening the enzymes. Biochemical and thermodynamic analyses indicated that only AncDAPDH-N4 exhibited greater thermal stability than and activity similar to those of native DAPDHs. Structural and sequence comparisons between DAPDH from Corynebacterium glutamicum (CgDAPDH) and the AncDAPDHs suggested that “quality of mutations” is a potential index parameter. In fact, the mutations introduced from CgDAPDH to AncDAPDH-N4 correlated highly with the mutations accumulated during the evolution process from mesophiles to thermophiles. These results suggest that, although there are several exceptions, the correlation coefficient can be used as an index parameter for screening high-functioning enzymes from sequence data.